Compaq DL590 - HP ProLiant - 1 GB RAM Technology Brief page 7

TC020702TB
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ECHNOLOGY RIEF
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Implementing 64-bit, 66-MHz PCI technology increases bandwidth to a theoretical 532 MB per
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second, double the bandwidth of 33-MHz implementations. Although 3.3-volt, 33-MHz cards
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may be plugged into the 66-MHz slots, no performance benefit will be achieved. In fact, doing so
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will slow down the PCI bus such that all slots on the same bus will operate at 33 MHz, potentially
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reducing the performance of any 66-MHz device in another slot on that bus.
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As long as the proper 64-bit drivers have been installed to interface with the Itanium system, 32-bit
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PCI cards may be plugged into the 64-bit PCI slots. However, the 66-MHz slots have been keyed
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so that 5-volt PCI cards cannot be inserted. This eliminates the potential to damage the cards by
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inserting them into the wrong slots.
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System Board Design
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The Itanium processor and its power module (Figure 5) are much larger than the 32-bit Pentium III
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Xeon processor and its power module. They are also much heavier. Compaq engineers worked
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closely with Intel to drive innovations in the processor board design so form factor, modularity,
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and serviceability would not be sacrificed to accommodate the larger footprint and weight.
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Figure 5: The Itanium processor and power module are much larger than the 32-bit Pentium
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For example, Compaq required the use of very high-density metric connectors to provide tool-free
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insertion and removal of the processor and memory drawer in the ProLiant DL590/64 server.
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Compaq also required that these connectors be placed on one side of the board. This enhances
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cooling by allowing the processor board to plug into a side plane instead of a midplane, which
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would restrict front-to-back airflow.
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A dual-sided design allows the processor board to accommodate the four Itanium processors,
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associated power modules, and a maximum of 64 GB of memory in a mirror-image configuration.
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Of course, the more powerful processor and greater memory capacity place enormous power
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To handle these power requirements, Compaq designed the I/O board (Figure 6) and the side plane
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with an innovative bus bar technology. The bus bar accommodates the high current and high-
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speed buses that are routed through the board while keeping the layer count and cost of the board
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down.
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Xeon processor and its power module.